若m n=3
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m+n=2mn=-42(mn-3m)-3(2n-mn)=2mn-6m-6n+3mn=5mn-6(m+n)=-20-12=-32
(9-2mn+2m+3n)-(3mn+2n-2m)-(m+4n+mn)=9-2mn+2m+3n-3mn-2n+2m-m-4n-mn=9-6mn+3m-3n=9-6mn+3(m-n)=9-6×(-1)+
(-2mn+2m+3n)-(3mn+2n-2m)-(m+4n+mn)=-2mn+2m+3n-3mn-2n+2m-m-4n-mn=(-2mn-3mn-mn)+(2m+2m-m)+(3n-2n-4n)=-
原式=-2mn+2m+3n-3mn-2n+2m-m-4n-mn=3(m-n)-6mn=3×2-6×1=0.
m的平方+mn=5----------1)mn+n的平方=-3----------2)1)×3-2)×2,得3m的平方+mn-2n平方=5×3-(-3)×2=21
先合并同类项,得3(m-n)-6mn+9,代入已知数据,有结果27
解题思路:将原代数式经过去括号后合并同类项,化简后代入数值计算即可。解题过程:
(-2mn+2m+3n)-(3mn+2n-2m)-(m+4n+mn)=-2mn+2m+3n-3mn-2n+2m-m-4n-mn=(-2mn-3mn-mn)+(2m+2m-m)+(3n-2n-4n)=-
(9-2mn+2m+3n)-(m+4n+mn)=9-2mn+2m+3m-m-4n-mn=9-mn+(m-n)=9-(-1)+4=14
m2+mn=-3①,n2-3mn=18②,①-②得:m2+mn-n2+3mn=m2+4mn-n2=-3-18=-21.故答案为:-21
64=MQ=1/2MP=1/2*4/3MNSOMN=4*2/1*3/4=6
作A点关于直线MN的对称点A′,连接A′B交MN于C,则AC+BC=A′C+BC=A′B,A′B就是AC+BC的最小值;延长BN使ND=A′M,连接A′D,∵AM⊥MN,BN⊥MN,∴AA′∥BD,∴
由mn-m=2得:2mn-2m=4与2mn+3n=7两式相减可得2m+3n=3
-MN(M^2N^5-MN^3-N)=-(-6)^3+(-6)^2-(-6)=258
mn的平方-m的平方n=mn^2-m^2n=mn(n-m)=-mn(m-n)把m-n=-3,mn=5代入上式,得-mn(m-n)=-5(-3)=15
2[mn+(-3m)]-3(2n-mn)=2mn-6m-6n+3mn=5mn-6m-6n=5mn-6(m+n)m+n=2mn=-3=-15-12=-27
已知mn=-1,m-n=4则(-2mn+m+n)-(3mn+5n-5m)-(m+4n-3mn)=-2mn+m+n-3mn-5n+5m-m-4n+3mn=-2mn+5m-8n=2+20-3n=22-3n
∵原式=-3(2n-mn)+2(mn-3m)=-6(m+n)+5mn∵m+n=-3,mn=2∴原式=-6·-3+5·2=28
3(2n-mn)+2(mn+3m)=6n-3mn+2mn+6m=6(m+n)-mn=6*-3-2=-20
点P(m,n)在反比例函数y=m/x的图像上n=m/m=1mn